Triclosan has a robust, yet reversible impact on human gut microbial composition in vitro.

Authors: Mahalak, Karley; Firrman, Jenni; LEE, JUNG-JIN - Children'S Hospital - Philadelphia, Pennsylvania; BITTINGER, KYLE - Children'S Hospital - Philadelphia, Pennsylvania; Nunez, Alberto; BOBOKALONOV, JAMSHED - US Department Of Agriculture (USDA); ARANGO-ARGOTY, GUSTAVO - Virginia Tech; ZHANG, LIQING - Virginia Tech; ZHANG, GUODONG - University Of Massachusetts; Liu, Linshu

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2020
Publication Date: 6/25/2020
Citation: Mahalak, K.K., Firrman, J., Lee, J., Bittinger, K., Nunez, A., Bobokalonov, J., Arango-Argoty, G., Zhang, L., Zhang, G., Liu, L.S. 2020. Triclosan has a robust, yet reversible impact on human gut microbial composition in vitro. PLoS One. 15(6): 1-22. https://doi.org/10.1371/journal.pone.0234046.
DOI: https://doi.org/10.1371/journal.pone.0234046

Interpretive Summary: Triclosan is an anti-bacterial chemical compound whose wide usage in consumer products over decades and its ability to be absorbed by the human body has led to concerns about its impact on human health. To address these concerns, we studied the effect of triclosan on the bacterial community of the human colon. To do so, we used a bacterial only, in vitro system to understand whether prolonged exposure to triclosan would have a large effect on the bacterial community, as well as whether that effect could be reversed after ending treatment. We found that the introduction of triclosan into the bacterial community caused a sharp decrease in bacterial population and the compounds they produce. Interestingly, we also found that this response was reversible over a 2-week period.

Technical Abstract: The recent ban of the antimicrobial compound triclosan from use in consumer soaps followed research that showcased the risk it poses to the environment and to human health. Triclosan has been found in human plasma, urine and milk, demonstrating that it is present in human tissues. Previous work has also demonstrated that consumption of triclosan disrupts the gut microbial community of mice and zebrafish. Due to the widespread use of triclosan and its ubiquity in the environment, it is imperative to understand the impact this chemical has on the human body and its symbiotic resident microbes. To that end, this study is the first to explore how triclosan impacts the human gut microbial community in vitro both during and after treatment. Through our in vitro system simulating three regions of the human gut; the ascending colon, transverse colon, and descending colon regions, we found that treatment with triclosan significantly impacted the community structure in terms of reduced population, diversity, community member survival, and metabolite production, most notably in the ascending colon region. Given a 2-week recovery period, most of the population levels, community structure, and diversity levels were recovered for all colon regions. Our results demonstrate that the human gut microbial community diversity and population size is significantly impacted by triclosan at a high dose in vitro, and that the community is recoverable within this system.